First things first, NEVER LEAVE YOUR DOG ALONE IN THE CAR! With temperatures nationwide having a heat index in excess 100 degrees most of the day, it is simply cruel to leave your dog in the car. This is a huge issue with me. I have broken into cars and taken dogs out and rehomed said dogs because of this. Inside of the car, with no AC, after about 3 minutes you can get temperatures in excess 130 degrees. This is no different than placing the dog in an oven. Plus it's illegal in most states.

Second thing, and this is another pet peeve of mine, place your dog into a harness or auto-kennel. Have you ever seen a dog who has flown through a windshield because the owner didn't have it strapped in and had a wreck? It's not pretty. I don't care how good a driver you are, if someone pulls in front of you and you have to slam on your brakes, the dog is gonna fly. Volunteering with pet rescue has afforded me seeing many dogs with missing or severely broken teeth from smashing into a dashboard. Treat your dogs like toddlers in a vehicle, at all times. Strap em in.

Thirdly, punishing your dog for freaking out doesn't really work, as you know. It only leads to more distress because you aren't understanding what they are trying to say and it frustrates them. They freak out, you freak out in turn and everything goes to crap. Been there, done that. If you have no fear of being bitten, I recommend gently grabbing the muzzle and talking very calmly. This means you might have to pull over and stop. While driving, your most important duty is to drive, so if your dog is hindering that, you stop driving first, then deal with the dog. Most dogs can calm down if you pull them to you and speak calmly to them, and hinder them from seeing the distressful situation. If you had a friend with a dog that she normally plays with, then maybe you could do some training sessions. Try doing this in a parking lot and have the dog walk by over and over and over. Every single time your dog freaks, do the focusing techniques. gently grab the face, turn the attention to you, blinder the dog with your hands if you have to. Use calm soothing words, not harsh voice. Bad dog reproach will not work here. You need to get the dog to understand that it's okay for a pooch to walk by, and there is no 'best' way, just the way that will work for your dog. You say she is highly social, so having a doggy buddy may help her get past this. Once she has calmed down, let her out of the car to go and smell doggy buddy and play a tiny bit. Then repeat. I recommend parking in the shade and having the windows down and AC on if the temperature outside is higher than 85 degrees in the sun.

This is a time consuming task, and you have to be consistant. Lack of consistancy on the part of the human is the major problem with dog training. Always remember you are talking two seperate foreign languages at the same time to your dog. Your audible language is foreign, however the dog can learn to recognize words by the sound, but what they mean to her may be different than what your intention is, so be consistant. Your body speaks another language to the dog, so make sure you use the same hand signals and watch your posture while training. If you give a certain hand signal when training for sit or stay, then use a very similar hand signal for stop or run away, you will confuse the hell out of the dog. Some dogs are highly intelligent, whereas some dogs are absolute dorks. Same goes for humans, heheh.

Just remember that you can stop the destruction instantly with an auto-kennel, and limit the hell out of the destruction with a seatbelt harness. And never ever ever leave your dog alone in the car. Go to the store and get your water, ice, and sodas and place them in a cooler BEFORE you get the dog and put her in. This will eliminate any 'need' to stop other than gas, and you can easily pay at the pump and never leave the area of the car. Good luck, and try counting to ten, because a barking dog is to me the worst noise in the world, and drives me bananas, so I empathize.